There are many processes in industry in which it is desirable to “react” (chemically or physically) a liquid with a gas. Most of such processes may differ significantly in detail, but many processes have in common the desire to provide intimate contact between the gas and the liquid and at a rapid rate. A rapid intimate contact may result in effective reactions and a fast reaction rate, both being desirable goals.
U.S. Pat. No. 6,004,386 discloses an apparatus for generating gas-liquid interfacial contact conditions for highly efficient mass transfer between a gas and a liquid. The disclosed apparatus includes a gas-liquid contactor assembly including: a hollow porous tube surrounded by an outer jacket defining a gas plenum between the jacket and the porous tube; a liquid feed assembly including a nozzle for injecting liquid into the porous tube in a spiralling flow pattern around and along the porous tube; a gas-liquid separator assembly at the first end of the porous tube including a non-porous degassing tube coaxially aligned with and connected to the porous tube, a gas outlet port coaxially aligned with the degassing tube to receive a first portion of gas flowing from the degassing tube, a first gas duct coaxially aligned with and connected to the gas outlet duct to convey the first portion of gas therefrom; and a liquid collection assembly. A second gas discharge assembly to collect and convey gas from the first end of the porous tube is also disclosed.
In U.S. Pat. No. 5,405,497 is disclosed a method of chemically reacting a liquid with a gas in a vortex. Here, a slurry or a liquid is introduced in a first end of a vortex, and a gas is introduced from exteriorly of the vortex into contact with the slurry or liquid in the vortex, so that a reaction between the slurry or liquid and the gas takes place. The treated slurry or liquid is removed from the second end of the vortex while any residual or carrier gas is removed from the first end of the vortex. Gas introduction may be accomplished through a porous surface of revolution (e.g. cylindrical or conical) wall surrounding the vortex, whereby the gas may be in minute bubble form when it enters the slurry or liquid.
However, neither from U.S. Pat. No. 6,004,386 or from U.S. Pat. No. 6,004,386 is it known to obtain an intimate contact between a gas and a liquid by the use of flow passages obtained from longitudinally extending interspaces of fibres extending longitudinally in a fibre housing.
The use of fibres extending longitudinally in the direction of a fluid flow and used for filtration of such fluid has been described in the prior art. U.S. Pat. No. 4,219,420 discloses an arrangement for filtering a contaminated fluid or medium. According to the disclosure of this patent a plurality of fibre bundles are located on a support and extend within a filter housing in direction between an inlet and an outlet of the housing. The fluid to be filtered is introduced through the inlet in a direction towards the outlet. The contaminated particles become arrested among the fibres as it passes through the plurality of fibre bundles. In order to improve the “depth effect” of the fibre bundles, the fibres may have different lengths. Here the quality of the filtered fluid depends on the density of the fibre bundles. However, in order to increase the quality of the filtration process, the density of the fibres must be increased, which requires more fibre bundles to be inserted into the filter housing.
An improvement to the filter of U.S. Pat. No. 4,219,420 has been proposed in EP 0 280 052. Here a filter housing comprises a supporting means with a plurality of fibre bundles attached to the supporting means and extending within the filter housing in direction between an inlet and an outlet. A flexible water-proof membrane is provided within the filter housing to constitute a pressure chamber. When pressurised during the filtration process, the membrane press the plurality of fibre bundles to form a frustrum-like filter chamber, and the fluid becomes filtered as it passes through the frustrum-like chamber. Here the density of the fibres and thus the quality of the filtration can be controlled by adjusting the pressure in the pressure chamber whereby the compressing of the fibres is adjusted.
Another filter having fibres extending longitudinally in the direction of the fluid flow, and wherein the density of the fibres is adjusted by compressing the fibres, is disclosed in WO 94/11088. Here the fibres are arranged within an opening defined by a retaining member, and a displacement member comprising a conical-shaped part is arranged in the centre of the fibres. By moving the displacement member in a direction along the fibres, the compressing of the fibres against the retaining member is adjusted whereby the density of the fibres and the quality of the filtration is controlled.
Thus, the principles of having a fluid filtration wherein a plurality of fibres extend longitudinally in the direction of the fluid flow, and wherein the quality of the filtration is controlled by adjusting the compression and thereby the density of the fibres is known.
The filtering device of U.S. Pat. No. 4,219,420 uses a pressure chamber in order to compress the fibres, whereas the filtering device of WO 94/11088 has a conical-shaped displacement member arranged in the centre of the fibres in order to compress the fibres against a retaining member. Both of these filtering devices are relatively expensive to produce.
However, in none of the above mentioned references describing filtering devices using fibres extending in the direction of the fluid flow has it been suggested to obtain an intimate contact between a gas and a liquid by the use of the flow passages formed between the fibres.
Thus, there remains a substantial need for an improved method of optimising gas-liquid interfacial contact, and a need for an improved device in which optimal conditions for gas-liquid interfacial contact can be economically created and controlled.